Drug Resistance in TB — MDR, XDR

A 42-year-old woman from Mumbai with MDR-TB (confirmed by culture + DST: resistant to INH and RIF) on second-line therapy for 6 months shows clinical deterioration and persistent positive sputum culture. Resistance to fluoroquinolone is suspected. Which investigation is most appropriate to detect resistance to second-line drugs and confirm XDR-TB status?

A 38-year-old man from rural Maharashtra presents with a 4-month history of persistent cough, fever, and weight loss despite 2 months of standard first-line anti-TB therapy. Sputum smear microscopy remains positive. Drug susceptibility testing reveals resistance to both isoniazid and rifampicin. Which is the most common mechanism of resistance to rifampicin in MDR-TB?

A 38-year-old male from Mumbai with sputum smear-positive TB is found to have MDR-TB on GeneXpert MTB/RIF. He is started on a standard MDR-TB regimen. Regarding the second-line anti-TB drugs used in MDR-TB treatment, all of the following statements are true EXCEPT:

A 38-year-old man from Delhi with newly diagnosed pulmonary tuberculosis is started on standard first-line ATT (HRZE). After 2 months of treatment, sputum smear microscopy remains positive. Drug susceptibility testing (DST) is performed and reports resistance to both isoniazid and rifampicin. What is the most appropriate next step in management?

A 42-year-old woman from Mumbai with MDR-TB has completed 18 months of WHO-recommended MDR-TB therapy (fluoroquinolone, bedaquiline, linezolid, and amikacin). Repeat sputum smear microscopy and culture remain positive. DST on the latest isolate shows additional resistance to fluoroquinolones and bedaquiline. What is the most appropriate next step?